GMC Repair: Catalytic Converter, catalyst system, oxygen sensor

Question
Hello...
I own a 2000 Cavalier and I recently took my car in due to the check engine light being on. The code came back with "Catalyst system efficiency below threshold". The jerkoff mechanic did not have the proper testing equipment and told me "it can't be that...the car only has 60K miles on it!" I am bringing it to my dealer (for a warranty repair) because I think it is the catalytic converter because I trust the readout from the car...I don't trust him!

My question is ...Is there any possible way this reading is false?

Thanks,
Neal

Answer
Anything is possible. it could simply be a faulty oxygen sensor or it could actually be a small restriction in tha cat. The dealer can perform a BACKPRESSURE test on the cat to determine if it is the cat.

I have seen faulty cats on vehicles with less mileage.